U.S. Rep. Stephen Lynch, D-South Boston; and U.S. Rep. Ed Markey, D-Malden, will square off in a Democratic primary on April 30 in the special election to replace John Kerry. ]

Two groups that have endorsed Democratic Senate candidate and U.S. Rep. Edward Markey have released a new poll showing Markey in the lead over his Democratic primary opponent, U.S. Rep. Stephen Lynch.

The poll commissioned by the League of Conservation Voters and NARAL Pro-Choice America, which support Markey, found Markey with a 14-point lead over Lynch, 42 percent to 28 percent among likely primary voters.

The poll also asked about some of the differences between Lynch and Markey. While both Democratic Congressmen have consistently voted with their party leadership, Lynch has a few notable dissents. He is pro-life and voted against Democratic President Barack Obama’s health care reform law, though he says he agrees with the goals of the reform. The poll found that 81 percent of likely Democratic primary voters prefer a candidate who supports abortion rights and three-quarters prefer a candidate who voted for the Affordable Care Act.

The poll also found close to 70 percent of voters were supportive of Markey’s efforts relating to oil and environmental issues.

Markey, the ranking member of the House Natural Resources Committee, was the lead congressional investigator on the BP oil spill, and pushed BP to make various disclosures. He has pushed Congress to close a tax loophole that allows companies importing tar sands oil to avoid paying a tax paid by other crude oil companies. He has tried to forbid Wall Street speculators from investing in energy commodities, a move he says drives up energy prices. His leadership on various environmental issues, including addressing climate change, has earned him endorsements from the League of Conservation Voters and the Sierra Club.

However, there is not a significant difference between Lynch and Markey’s voting records on environmental issues. According to the League of Conservation Voters, Lynch voted in favor the group’s positions 94 percent of the time throughout his career – the same “lifetime score” as Markey.

The poll of 613 likely Democratic primary voters was conducted by the Garin-Hart-Yang Research Group Feb. 26-27 and has a margin of error of 4 percentage points.